The invention relates to an integrated memory circuit, having a high-voltage switch, an input of which is connected to a programming voltage generator and an output of which is connected to an erasable programmable memory, which switch includes a first and a second transistor, control electrodes and first main electrodes which are cross-wise interconnected in order to route charge in a step-wise fashion from the input to the control electrode of one another under the control of mutually complementary clock signals which are coupled to the respective control electrodes via respective capacitances, the output being connected to one of the control electrodes. The invention also relates to a high-voltage switch which is suitable for use in such a memory circuit. A switch of this kind serves to couple a point carrying a high programming voltage to or to disconnect such a point from a programming voltage input of the memory. Because an excessively fast increase of the programming voltage across the memory has an adverse effect on the service life of the memory, the switch should more or less gradually build up the full programming voltage across the memory.
Such a memory circuit and switch are known from: Donaldson, D. D. et al; "+5 V-Only 32K EEPROM", ISSCC Digest of Technical Papers, pp. 168-169, February 1983. In the known memory circuit the first transistor is of the depletion type and the second transistor is of the enhancement type. The second main electrode of the first transistor is connected directly to the input, the second main electrode of the second transistor being connected to the input via the current channel of the first transistor. The alternating clock signals on the capacitances step-wise build up a voltage at the relevant junction point by routing charge, via the current channels of the transistors, from the input to the junction point of the control electrode of the first transistor and the first main electrode of the second transistor, which junction point is coupled to the output. Because the first transistor is of the depletion type, the switch already operates in response to a clock signal of low amplitude.
It is a drawback of the known memory circuit that the depletion-type transistor necessitates an additional masking step in the manufacture of the integrated circuit, which has a cost increasing effect. A further drawback of the known memory circuit is that the switch is susceptible to crosstalk on the clock lines, because the switch already responds to clock signals of low amplitude. Because the switch is arranged in the vicinity of other active circuits on the chip, such crosstalk is always present to some extent. Therefore, it is an object of the invention to provide a memory circuit in which the switch is simply realized and operates reliably despite crosstalk on the clock lines.